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rutherford model


daniela celaya

on 11 February 2013

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Transcript of rutherford model

Rutherford model Daniela Celaya
Patricia Soto Ernest Rutherford publishes his atomic theory describing the atom as having a central positive nucleus surrounded by negative orbiting electrons. This model suggested that most of the mass of the atom was contained in the small nucleus, and that the rest of the atom was mostly empty space. Rutherford came to this conclusion following the results of his famous gold foil experiment. This experiment involved the firing of radioactive particles through minutely thin metal foils (notably gold) and detecting them using screens coated with zinc sulfide (a scintillator). Rutherford found that although the vast majority of particles passed straight through the foil approximately 1 in 8000 were deflected leading him to his theory that most of the atom was made up of 'empty space'. gold foil reich-chemistry.com
http://www.daviddarling.info/encyclopedia/ SMALL biography experiment The Rutherford model Bibliography is a model of the atom devised by Ernest Rutherford. Rutherford directed the famous Geiger-Marsden experiment in 1909, which suggested, upon Rutherford's 1911 analysis, that the so-called "plum pudding model" of J. J. Thomson of the atom was incorrect. Rutherford's new model for the atom, based on the experimental results, contained the new features of a relatively high central charge concentrated into a very small volume in comparison to the rest of the atom and with this central volume also containing the bulk of the atomic mass of the atom. This region would be named the "nucleus" of the atom in later years. Born in the land down under, Ernest Rutherford grew up with his large family in New Zealand consisting of six brothers, five sisters, his father James Rutherford his grandfather His mother, née Martha Thompson, and her mother. When he was 16, Rutherford took entered Nelson Collegiate School. After only a few years, he was awarded a scholarship and enrolled into the University of New Zealand. It was there that he double majored in Mathematics and Physical Science, and with his further achievements, he earned another scholarship to enroll into Trinity College. but But there appeared something terribly wrong with Rutherford's model of the atom. The theory of electricity and magnetism predicted that opposite charges attract each other and the electrons should gradually lose energy and spiral inward. Moreover, physicists reasoned that the atoms should give off a rainbow of colors as they do so. But no experiment could verify this rainbow.

In 1912 a Danish physicist, Niels Bohr came up with a theory that said the electrons do not spiral into the nucleus and came up with some rules for what does happen. (This began a new approach to science because for the first time rules had to fit the observation regardless of how they conflicted with the theories of the time.)

Bohr said, "Here's some rules that seem impossible, but they describe the way atoms operate, so let's pretend they're correct and use them." Bohr came up with two rules which agreed with experiment:

RULE 1: Electrons can orbit only at certain allowed distances from the nucleus.

RULE 2: Atoms radiate energy when an electron jumps from a higher-energy orbit to a lower-energy orbit. Also, an atom absorbs energy when an electron gets boosted from a low-energy orbit to a high-energy orbit Key Points The atom's electron cloud does not influence alpha particle scattering.
Much of an atom's charge (specifically, its positive charge) is concentrated in a relatively tiny volume at the center of the atom, known today as the nucleus.
The magnitude of this charge is proportional to (up to a charge number that can be approximately half of) the atom's atomic mass - the remaining mass is now known to be mostly attributed to neutrons. This concentrated central mass and charge is responsible for deflecting both alpha and beta particles.
The mass of heavy atoms such as gold is mostly concentrated in the central charge region, since calculations show it is not deflected or moved by the high speed alpha particles, which have very highmomentum in comparison to electrons, but not with regard to a heavy atom as a whole -Rutherford’s work suggested the existence of the positive proton in 1914 but its existence wasn‘t detected until 1918 when advances in technology allowed the scientists to study the nature of the atom in more detail.
-Other technological advances allowed the scientists to search for other subatomic particles. One machine in particular, a mass spectrometer, allowed the scientists to analyse an element that has more than one atomic mass.
-Once the scientists knew the mass of a proton and the charge on any nucleus they realised that something else must exist in the nucleus to stop the protons from flying apart. By 1920 scientists were using the name neutron for this other particle in the nucleus but no one was sure just what it was. However, they continued their search and, in 1935,
-James Chadwick received the Nobel Prize for his discovery of the neutron, the existence of which had been predicted by Rutherford. technological advances
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